Telephone-exchange system



C. B. FOWLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV. I9, 1920. 1,398,589.

Patented Nov. 29,` 1921.

w. www .E WN. NNQWNHSOJ .w s.. .I um WI (7a/ence row/ef UNrrEn sra'rrls CLARENCE B; FOW'LER, `NEW YORK, VVN.

PATENr OFFICEQ Y., ASSIGNOR TO WESTERN ELECTRIC .i i

COMPANY, INCORPORATED, OF NEW' AYORK, N.Y Y.,IAV CORPORATION VOF NEW YORK.

TELErHoNnfEXcHAnGE sYs'rElvn Specification of Letters Patent. Ptglltd NOV. 29,

Application filed November 1e, 1920. serial 110.4251582.

To alt whom t may concern B e it known that I, CLARENCE B. FowLnR, a cltlzen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useiullmprovements in Telephone- Exchange Systems, of which the following is a vfull,cle'ar, concise, andexact description. Y

This invention ...relates telephone ex# change systems and particularly to a new and improved toll switching trunk circuit for connecting a common battery toll switchboard with a magneto switchboard.'

Previous to this invention, it vwas the practice 'in establishing a trunk'connection between a common battery toll switchboard and a magneto switchboard, to use a toll switching trunk, of the type regularly used in makingrconnection with a common bat- Used 'in this way, the trunk supervisory signal did not function aswhen used for a common battery connection, necesv'sitatinggrtherefore, monitoring by the operator iny order to assure proper super-v vlsion; j

Itis an obJect'of this VVinvention to prof vide a trunk circuit which may be used for'extending'a connection from a commonv battery toll switchboard4 to a magneto switchboard, and which will have all the advantageous features of common battery board.Y Y

To furthe'rgattain this object in accord-VA ancewith another featureof this invention, means is provided so that a subscribers station oniaV magnetov line maybe selected and signaled from the tollswitchboard.

In accordance with a third feature of theinvention, there V1s a provision of means whereby, in the event of the called line 'beying found busy,. the trunk supervisory signal of the connecting toll cordn circuit v may be caused to flash intermittently.

tion and accompanying drawing in which vof two sections, with inductive n'lagnetic coupling consisting of a repeating coil'l9. The inductive fcoupling might, however, be

- of the electrostatic type, consisting Vof a condenser. It terminates in a-plug 11 at anoperators position ofa magneto'switchboard, and may be one of a plurality of similar circuits. 'It is adapted toextend" connections from a cord circuit vA ,atfthe' toll switchboard to any one ofa plurality there is shown,l a toll 1 of magneto subscribers lines terminating at the B or'switcliing'position of. azmag,

neto switchboard,oneof which, @,lis 'shown i connected toi a 'jack 12 at the contacts of i which is shown connected aline signal l5," which may beactuated by the operation of a magneto generator ata subscribersstation,'30. A busy back circuit D terminat-- ing kin a jack 34' within reach of the magneto switchboard operatorY is 4also shown. When the called subscribers line isfound engaged, the plug 11 is inserted into the jack 34 whereby aninterrupter 25 causes interrupted current to be transmitted over trunk B causing thereby Van intermittent actu-ation of a trunkxsupervisory signal '32 in the toll cord circuit AL l It is thought that thisinvention maybe more fully understood from the following *l j g description of the operation of the system as. shown on the drawing. f f' When the toll operator in controljoflthei cordcircuit A'desires to Vextend a connection to Athe :subscribers station 30 shown connected to line C.ga` trunk assignmentwill be obtained fromA the operator at the magneto switchboard in control of the incoming end plug 1 into' jack 2,'which causes the operation of relay `3 over the following circuit:

n from grounded battery through resistance 5,

sleeve contacts of plug l'andjack 2, 'and winding of relay 3 toigroundr Relay 3, irloperate l ing, causes the illumination of lamp 7 over the following circuit: Jtrom grounded battery through lamp 7, normal Contact ci relayv9 and right-hand alternate contact of relay 3 to ground. The illumination of lampv relays 14 and 9, sleeve contacts oplug 11` and jack 12,l and resistance 28 to ground.

Y Relay 14 being marginal does not obtain sul"- iicient current in this circuit to operate, but

relay 9 operates and by opening 'its normal AContact extinguishes lamp 7. rlhe lett-hand alternate contact of relayv 9V is. closed and causes the slow operating relay 16 to operater over anobvious circuit. Relay 9 is 'oiz the slow o Deratinvty Je so that the tin and.

b J l ring conductors will not be connected through until the plug 11 is completely inserted in jack 12. Otherwise relay 21 might operate from rbattery in the sleeve circuit, due to a momentary crossing of the plugand jack conductors, when'the plug is being inserted.Y The ,operation or' relay 16 closes a ,through circuit for the tip and ring con ductors and establishes a conversational f path from cord circuit A to the subscribers station 30. "The insertion ot vplug 11 into jack 12 also Causes the disconnection of line signal 15 at the normal contacts of jack 12.

The toll operator after inserting plug 1 into Jack 2 actuates the ringing key 37, ring- A*ing according to the necessary code to select the calledv subscribers station 30, which is connected'to the party line C. i The path oit the ringing current may betraced tollows.: from Vsource of ringing current 13, lower alternate contact ot keyY 37, ring` contacts of plug 1 'and jack 2, lower'normal coni tact of relay 22, winding of repeating coil' 19,

upper normal contact ot relay 22, tip contacts of jack 2 and plug 1, contact of key 37 to ground. Ringing current will be induced in the secondary windings of repeating coil 19 and willhe transvInitted over the tipy and ring conductors in-1- cluding Vthecontacts ot relay-16,1t1p and ring l contacts of plug 11 andjack 12, and the tip andiring conductors of 'line circuitC to bell 6 at substation 30. Station 30, upon the removal of tlierreceiver from the hook is now in conversational connection through the repeat# f, ing coil 19 with cord circuitAandthetoll line `(noti-shown) with which the answering end 'of cord circuit (not shown) is connected. On completion ot the conversation, key 31 at station'30 is-actuated and then the 'magneto generator 26 is operated.` Current is then transmitted over both the tip` and ring conductors of line circuit C as follows; from and upper alternate ground through the upper alternate Contact of key 31, armature and contact of generator`26 to the ring conductor, also through .the lower alternate contact of key 31, to the tip conductor. This current passes in parallel over both-tip and ring conductors, 4tip and ring contacts of jack 12, plug 11, contacts of relay 16, upper and lower right-hand windings of repeating coil 19 to the center point between these windings and thence through the winding ot relay 21 'to ground.v Relay 21 operates to cause the operation of relay 22 over aniobyious circuit connecting thereby battery and ground to the Yring and y tip conductors of trunk circuitB as follows:

from grounded battery through the lower winding ot retardationcoil 29, lower alternate contact of relay 22, ring contacts of jack 2 Vand plug 1, winding of relay 27, tip'con-V ltacts ofp'lug 1 and jack 2, upper alternate Contact of relay 22, andupperwinding of retardationcoil V29 Ato ground. "Relay 22, upon operating locks up throughthe following path: from grounded-battery through the'winding and middle alternate contactof, relay 22, vcontact of relay 14, and left-hand alternate contact of relay 3 to ground. Relay 27 operates and causes the Villumination of lamp 32 over an obvious circuit. The toll operator upon noting the glowing of lampl 32,'connects an operators telephone set (not shown) to the cord circuit A by actuationof listening key l23. Y Although relay22'is *op-v` erated, opening thev tip and ring conductors,

at its'upper and' lower normal'contacts, a

talking path'is still provided through con- `densers 4 and 10. "Upon ascertaining that the glowing of the lamp 32 is afdisconnect signal, the toll operator withdraws plug 1 from j ack 2 and releasesrelay 3. This again causes the'illumination of lamp 7y which is now a disconnect signal to themagneto switchboard operator who withdraws plug 11 from jack 12, thereby returning all apparatus to normal. If however, a disconnec-V tion isnot desired the operator withdraws plug 1 only for an instant, so as to release relay 3 momentarily, and thereby open the lockingcircuit of relay 22, so that this jre-- lay will release and causerthe' extinguishing of the supervisory lamp Y It, when the toll operator in contr kol of cord circuit4 A, requestsV over the call wire/circuit (notshown) a connection tostation 30,

Vit is found that the line circuit Gis engaged,

the' magneto switchboardioperator, instead of inserting plug 11 into jack 12, inserts it intoV jack 34, causing thereby the operation of relays 36, 9 and 14- over thek following circuit: from grounded battery through'. the winding of relays 14 and 9, sleeve contacts `of plug 11 and jack '34, resistance 35 and winding of relay 36 to ground. Under this Y condition, relay 14 now Soperates Ydue to the low resistance ofl resistance and relay Bti- TWhen relay 36 operates, it closes an obvious vcircuit from interrupter 25 through the Winding ot relay 2li causing the latter relay to opcrate intermittently. Rel ay 9 upon operating again causes the operation oil slow operating relay 16 which connects through, at its alternate contacts, the tin and ring conductor of the trunk circuit n. rl`he intermittent operation oi relay 24 causes the intermittent operation of relay 21 over the following cii` at the contact of relay 14E. The intermittent operation of relay 22 causes the intermittent operation of relay 27, over the circuit previously traced, and the flashing of trunk supervisory lamp 32. The toll operator observ-V ing the liashing is advised thereby of the busy condition of the line circuit C and upon withdrawing` the plug 1 from jack 2 causes the release'oi1 .relay 3, and the lighting of lamp 7 as a disconnect signal. Plug 11 is then withdrawn from jack 34, and all apparatus is restored to normal. f

Cord circuiti A is also provided with a relay 18, which in series with tue condenser 17 is connected across the line. This relay when energized by ringing current incoming from the connected toll line-(not shown), causes the operation of relay 8, and the lighting ot lamp 32 over obvious circuits. Relay 8 locks upthrough a circuit including its own contact and the normal Contact oi lrey 23. The operator upon noting the glowing of lamp 32, operates listening key 23 to supervise the connection and by so doing', opens the lockingcircuit oi relay 8 and extinguishes lamp 32.

That is claimed is:

1. ln'a telephone exchange system, a subscribers line circuit avsubscribers station on said line, a source ot current at said station, an Operators position, a cord circuit associated with said operators position, a supervisory signalingl device associated with said cord circuit, a link circuit for extending a. connection 1from said cord circuit to said line circuit, means for operasupervisory signaling device. 3. Ina telephone exchange system, a subting said supervisory signaling device 'from said station in response to the source ofcurrentA thereat so as to be steadily operated, interrupter circuit for connection tother link circuit, and means for intermittently operating said supervisory signaling device when said link circuit interruptor circuit.

2. Ina telephone lexchange system, a sub-4 scribers line circuit, a subscribers station on said dine, a source of current at said station, an operators position, a cord circuit associated with said operators position, a supervisory signaling device associated with said cord circuit, a link circuit` for extending a connection 'from said cord circuit to saidy line circuit, a relay responsive to the source oi current `at the subscribers station, a locking circuit for said relay, means vfor causing the rela-yfto loclrthrough said circuit, means for causing the said supervisory signalingidevice to be steadily operated in response to the actuation-of said relay, an interrupter circuit for -connection is connected to said to the link circuit and means for opening the Vlocking circuit when thetrunk circuit is connected to the interrupter circuit there? by operating said relay lintermittently tocause an intermittent operation of said scribers line circuit, a Jcord circuit, a supervisory signaling device associated with said cord circuit, a link circuit for extending a connection to said line circuit, an interrupter circuit for connection to the linkcircuit, a `relay responsive to current inthe trunk conductors, said relay controlling said supervisory signaling device a locking circuit ior said relay, asecono relay controlling said locking circuit, means associated with said line circuit for preventing the operation oi the said second relay when the link circuit is connected with the line circuit,

and means associated with said interrupter circuit foroperatingsaid second relay when the link circuit is `connected to the interrupter circuit, to open the locking circuit of the first mentioned relay for placingsaid first mentioned relayunder controlv of said interrupter circuit tointermittently operate said supervisory signal. l f

In witness whereof, -Ihereunt'osubscribe my name this 9th day ot-November, A. D.,

CLARENCE B.. VFOVVLER. 

